Engines in aircraft normally require high quality lubrication which can be achieved only by forced circulation or pressure lubrication systems. This requires a tank from which the lubricating fluid is supplied, a pump and a circulation network for movement of the lubricating fluid between the tank and the various bearings of the engine. In a conventional oil-filled tank used only for normal flight, oil is drawn off through an outlet at the bottom of the tank to ensure a continuous supply at all times. However, to obtain a continuous supply of oil from the tank in an aircraft which turns at steep angles or flies inverted, outlets must be placed at various positions in the periphery of the tank, or movable parts must be used in order that at least one outlet will be in the lowest part of the tank and thus submerged no matter what orientation is assumed by the tank with respect to the downward sense of the vertical. The conventional tank therefore requires a complicated configuration.
Accordingly, there is a need to provide an improved pressure lubrication system of aircraft engines which may be useful for inverted flight and/or other flight attitudes.